The present invention concerns a propulsion system for motor boats and, in particular, a so-called xe2x80x9cV-drivexe2x80x9d type propulsion system.
In propulsion systems of this type, anyway known for many years, the driving shaft exits from the motor unit towards the bow of the hull and is connected, directly or indirectly, to a reversing gearbox or inverter. From the latter thus exits the propeller shaft of the propeller, obviously turned towards the stern of the hull.
Instead, in the more conventional propulsion systems, the kinematic chain is basically aligned in sequence from the motor unit until the propeller. An example of these more conventional propulsion systems is described in the Italian patent application no. MI96A-001151 and in the corresponding patent publications no. U.S. Pat. No. 5.944.569 and no. EP-A-811551.
Compared to the conventional propulsion systems, the V-drive type systems have various advantages, among which is the setting back of the motor unit weight and the possibility of reducing the propeller axis inclination.
In the case of direct connection between the driving shaft and reversing gearbox, in which the latter is integrally connected with the motor unit, these system types also allow a considerable saving of internal space.
Nevertheless, propulsion systems of this type give particular problems during the assembly stage, especially in obtaining the correct alignment between the motor unit and the rest of the propulsion system, i.e. the reversing gearbox and propeller shaft.
In fact, the propeller shaft exiting from the reversing gearbox remains under the motor unit and the correct alignment between the propeller and driving shaft axes cannot be checked visually. For this reason, it is often necessary to connect the driving shaft indirectly to the reversing gearbox, for instance interposing cardan shafts that tolerate even slight alignment errors. However, this solution compromises some of the advantages offered by the V-drive type systems.
The task of the present invention is to provide a V-drive type propulsion system that obviates the drawbacks of the known technique.
Within the scope of this task, one object of the present invention is to provide a propulsion system for motor boats that finally solves the alignment problems between the motor unit and the remaining part of the propulsion system.
Another object of the present invention is to provide a propulsion system for motor boats that simplifies the assembly operations of same propulsion system on the hull.
A further object of the present invention is to provide a propulsion system for motor boats that also allows the particularly simple and quick variation in the axis inclination of the propeller with respect to the hull bottom.
These objects are achieved by the present invention, which concerns a propulsion system for motor boats, of the type comprising at least one motor unit, at least one reversing gearbox connected to the shaft existing from the motor unit, at least one propeller shaft to transmit the movement from the reversing gearbox to the propeller of the system, and at least one support member for the propeller shaft to be fixed to the hull bottom near the propeller, characterized in that it comprises means to mechanically connect together the at least one motor unit and the support member for the propeller shaft.
In this way a single block is produced which combines the motor unit, the reversing gearbox and the support member of the propeller shaft in one integral structure, thus allowing the correct alignment between motor unit and propeller shaft already during the construction stage of the propulsion system,
According to the preferred embodiment of the present invention, the propulsion system is of xe2x80x9cV-drivexe2x80x9d type and, even more preferably, the reversing gearbox is integral with the motor unit. Hence a particularly compact xe2x80x9cclosed ringxe2x80x9d structure is produced. which considerably simplifies the installation of the propulsion system on any motor boat. This also allows an advantageous reduction in the length of the propeller shaft.
In a possible embodiment of the present invention, the means of mechanical connection include at least one portion of the support member that protrudes inside the hull.
The means of mechanical connection can also include one or more devices for the support of the motor unit.
According to a possible embodiment, the propulsion system includes one or more devices that allow adjustment of the propeller shaft inclination with respect to the bottom of the motor boat on which it is assembled. In fact, being able to work on a single integral structure makes it very simple to vary the inclination of the propeller shaft, and hence the propeller axis, with respect to the hull.
According to a further possible embodiment, the means for mechanically connecting together the motor unit and the support member for the propeller shaft include one or more hydraulic actuators. This allows the closed ring structure of the propulsion system to pivot around an axis and, consequently, to adjust the inclination of the propeller shaft also during running. In this case the transmission is made xe2x80x9cfrimmablexe2x80x9d, according to the nautical terminology used for speedboats, i.e. the trim assumed by the propeller axis with respect to the water surface, may be adjusted.